A doctor typically draws sends drawn blood in standard centrifuge tubes to the laboratory that does the actual analysis. Such tubes are small cylindrical bottles made of glass or plastic and provided with a tight removable cover. As a rule they are simply put in a standard cardboard shipping box and surrounded with some sort of packing. In order to accommodate tubes of different sizes, as certain tests require a larger volume of blood than others but the laboratory normally only supplies a single type of shipping box, it is standard to pack with standard plastic peanuts, as in this manner any space around the bottle(s) can be filled.
Such a system has several disadvantages. First of all, if only a single tube is being shipped, there might not be enough packing material to hold it in place, so that the tube will be able to work its way into a position where it can be damaged or where it can bump against another tube. If several tubes are being sent, the user must discard the extra packing. At the laboratory end, digging out the tubes is inconvenient and, in some instances, a tube is so buried in the packing material that it is missed.